The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingTerminals of ecu
Check instrument panel junction block (main body ecu)
Measure the voltage of the connectors.
If the result is not as specified, the junction block
(main body ecu) may have a malfunction. ...
A/f sensor circuit slow response (bank 1 sensor 1)
Hint:
Sensor 1 refers to the sensor mounted in front of the three-way catalytic
converter (twc) and located
near the engine assembly.
Description
Refer to dtc p2195 (see page es-292).
Monitor description
After the engine is warmed up, the ecm performs air-fuel ratio feedback
contro ...
Reassembly
Hint:
When installing the ornament plate and emblem, heat the
radiator grille, ornament plate and emblem using a heat light.
Standard heating temperature
Notice:
Do not heat the radiator grille, ornament plate and
emblem excessively.
Install radiator grille emblem
Attach ...